1. Field of the Invention
The subject invention generally relates to a lignocellulosic article and, more particularly, to a lignocellulosic article and a method of producing the lignocellulosic article with a binding agent comprising a high temperature polymerization (HTP) polyol and an isocyanate component.
2. Description of the Related Art
Lignocellulosic articles, such as oriented strand board (OSB), oriented strand lumber (OSL), particleboard (PB), scrimber, agrifiber board, chipboard, flakeboard, and fiberboard, e.g. medium density fiberboard (MDF), generally have desirable physical properties, such as strength and stability. Such lignocellulosic articles are typically produced by blending or spraying lignocellulosic pieces with a binder composition, e.g. a resin. After blending or spraying the lignocellulosic pieces with the binder composition, pressure and heat are applied to the lignocellulosic pieces and the binder composition to form the lignocellulosic articles.
The lignocellulosic pieces can be in the form of chips, shavings, strands, scrim, wafers, fibers, sawdust, bagasse, straw and wood wool. When the lignocellulosic pieces are relatively large in size, e.g. from 1 to 7 inches, the lignocellulosic articles produced by the process are known in the art under the general term of engineered wood. These engineered woods include laminated strand lumber, OSB, OSL, scrimber, parallel strand lumber, and laminated veneer lumber. When the lignocellulosic pieces are relatively small, e.g. typical sawdust and refined fiber sizes, the lignocellulosic articles are known in the art as particleboard and fiberboard, e.g. MDF. Other engineered woods, as scrimber, employ thin, long, irregular pieces of wood having average diameters ranging from about 2 to 10 mm and lengths several feet in length. Regardless of the particular type of lignocellulosic article, binder compositions are typically utilized to bond the lignocellulosic pieces together.
Binder compositions that have been used for making such lignocellulosic articles include phenol formaldehyde (PF) resins, urea formaldehyde (UF) resins and isocyanates. Conventional binder compositions based on isocyanates are commercially desirable because they have low water absorption, high adhesive and cohesive strength, flexibility in formulation, versatility with respect to cure temperature and rate, excellent structural properties, the ability to bond with lignocellulosic materials having high water content and, importantly, zero formaldehyde emissions.
However, conventional binder compositions based on isocyanates require the inclusion of release agents. In particular, when pressure and heat are applied to the lignocellulosic pieces and the binder composition to form the lignocellulosic articles, metal plates are utilized. Isocyanates adhere to the metal plates, which has a deleterious impact on the production of the lignocellulosic articles. For example, if the binder composition adheres to the metal plates, the lignocellulosic articles have undesirable and uneven surfaces. In addition, the metal plates must be scraped and/or cleaned prior to producing another lignocellulosic article. As such, release agents are typically included within the binder composition or applied on the metal plates prior to producing the lignocellulosic articles. Release agents introduce additional costs and processing steps in the method of producing lignocellulosic articles. Moreover, when release agents, which generally comprise soap or wax emulsions, are applied on the metal plates prior to producing the lignocellulosic articles, such release agents pose additional risks, e.g. risks of fire, in view of the elevated temperatures to which the metal plates are heated while producing the lignocellulosic articles.